1. Field of the Invention
The present invention relates to a display control apparatus and method and, more particularly, to a display control apparatus and a display control method of a display apparatus which uses, for example, a ferroelectric liquid crystal as an operational medium to display and update.
2. Related Background Art
Hitherto, a CRT display is mainly used as a computer dips lay. However, since the CRT display needs a certain degree of length in the thickness direction of the display screen, it is difficult to miniaturize the whole display apparatus. A liquid crystal display has been proposed (hereinafter, referred to as an LCD) as a display to solve such a drawback. At present there are several types of LCDS. For example, there are a high time division driving method (STN) of the twisted nematic liquid crystal and a method (NTN) to perform a black and white display as a modification of the STN method. There is also a plasma display method using a plasma discharge. In all of the above methods, the in,age data transfer is the same as that of the CRT and the screen updating method is based on the non-interlacing method using a frame frequency of 60 Hz or higher. Therefore, the total number of scanning lines forming one screen lies within a range from 400 to 480. An LCD of a large size such that the total number of scanning lines is equal to or larger than 1000 has not yet been put into practical use. This is because since the display elements of those display panels do not have a memory performance in terms of the driving principle, a refresh cycle of the frame frequency of 60 Hz or higher is needed to prevent a flickering. Therefore, one horizontal scan time is a short time of 10 to 50 .mu.sec or less and, when the number of scanning lines is increased, a good contrast is not derived.
The ferroelectric liquid crystal display apparatus (hereinafter, referred to as an FLCD) can realize a display of a large screen and a high fineness which fairly exceeds the above display apparatus. However, since a frame frequency to drive the FLCD is low, a high-order interlace (multi-interlace) cannot help being used.
However, when image data is displayed by using the multi-interlace, what is called a "flickering" occurs when an object (for example, a cursor, character, icon, another figure, or the like) displayed in the screen is moved or newly produced, so that there is problem such that the display quality is remarkably deteriorated.
There is what is called a "partial rewriting" method as means for preventing the "flickering" of an object in the screen in the multi-interlace mode. According to this method, in the movement, production, or the like of an object in the screen, a line region in which the display of the screen changes is temporarily displayed in the non-interlace mode. As a method of realizing such a partial rewriting method, for example, there have been proposed the methods as disclosed in JP-A-63-65494, Japanese Patent Application No. 63-285141 (U.S. Pat. No. 5,091,723), and the like. However, to consideration is made with respect to a counter measure in case of displaying a moving image, a still image, or the like on the same screen.
At present, on the other hand, since the FLCD has a feature such that the ferroelectric liquid crystal can hold only binary values, a process such that analog gradations are provided for color by varying an applying voltage or the like cannot be performed. Therefore, only the 16-color display of each bit of RGBI (I denotes a white bit) can be executed. When the user tries to display a moving image or the like, a lack of power of express ion causes a problem.